1. Field of the Invention
The present invention relates to a new device which is effective in isolating gas delivery apparatus used in the dental office from a patient's skin and mucous membranes. The device is especially useful in preventing cross-contamination of patients from contaminated anesthetic equipment.
2. Description of the Prior Art
Increasing concern over the role of the dental profession in the transmission of infectious disease has focused attention on the proper sterilization of dental equipment. One instrument that has largely escaped consideration is the nitrous oxide gas machine with its attendant tubing, nasal hood, and reservoir bag. Recommendations for routine cleaning of nitrous oxide equipment vary from spraying the nasal hood with scented alcohol to washing all rubber goods with soap and water. It is questionable whether these or other techniques currently in general use provide adequate disinfection. Microbial cross-contamination during sedation with nitrous oxide has not been considered a major problem, but related inhalation devices have been linked with nosocomial infections.
Anesthetic and other inhalation devices are clearly sources for the iatrogenic transmission of infectious disease. Microorganisms have been recovered from virtually every portion of the anesthetic breathing circuit. The microorganisms that have been isolated from anesthetic and inhalation equipment include known pathogens, such as Candida albicans, Clostridium perfringens, Escherichia coli, Haemophilus influenzae suis, Klebsiella pneumoniae, Mycobacterium tuberculosis, Pseudomonas aeruginosa, Salmonella montivedeo, Staphylococcus aureus, Streptococcus pyogenes, and the Viridans streptococci. It can be assumed that various mycoplasma, viruses, and other organisms not evaluated may also be present in the anesthetic devices.
Accordingly, the possibility exists that dental practitioners using nonsterile equipment may be facilitating the spread of infectious disease. This possibility was examined by Yagiela et al., JADA, Vol. 98, February 1979, pp. 191-195, who administered nitrous oxide and oxygen to patients for 30 minutes. In nine of 21 instances, bacteria morphologically identical with organisms isolated from the nasal mucosa of the patients were cultivated from the used nasal hoods. Further experiments with an artificial breathing system designed to mimic human respiration showed that bacteria deposited on nasal hoods were routinely dislodged and inspired during subsequent use.
Yagiela et al. concluded that traditional cleaning methods involving soap and water rinses, alcohol sprays or swabs, or commercial cleaners may provide some degree of disinfection, but they cannot be relied on to produce total sterility. Yagiela et al. propounded that more effective techniques are generally impractical. Tubing and nasal hoods are easily damaged by high temperatures in an autoclave, and monetary and space requirements for sterilization with ethylene oxide are prohibitive. They proposed that perhaps the best compromise between effectiveness and practicality is to disinfect with a "cold" germicidal solution and identified alkaline glutaraldehyde as the most suitable preparation available. They observed that glutaraldehyde does not coagulate proteins, and it remains active in the presence of mucus and blood. Deterioration of rubber and plastic is not an important problem. Because of its low surface tension, glutaraldehyde penetrates small spaces easily and is readily removed by rinsing with water. Finally, alkaline glutaraldehyde is the most effective germicide in use; a ten-minute submersion at room temperature is sufficient to kill all microorganisms, with the exception of spores, which may require as long as ten hours of submersion.
More recently, and as discussed by Milgrom et al., International Dental Journal (1986) 36, 71-76, both AIDS and hepatitis have caused considerable stress and worry to general practitioners and specialists in urban areas throughout the world. The recognition of the hazard is paramount if appropriate precautions to protect dental office personnel are to be taken.
Because so little is known about the spread of AIDS and because carriers remain unidentifiable to the dentist, precautions must be taken. It is believed that the causative agent is a virus. Control measures to prevent contact with saliva and blood are appropriate in higher risk individuals. Surgical gloves or doubled examination gloves are required for all procedures. Glasses, masks and gown should be worn if aerosolization or splatter will take place. All contaminated material should be sterilized and disposed of properly. All instruments including hand pieces should be heat sterilized although glutaraldehyde products appear to be an acceptable substitute when heat sterilization is impossible.
Currently many different gas apparatus are used to deliver gas to people and animals. For example, nitrous oxide or laughing gas is used in dental offices and delivered to patients through a device called a hood that covers a patient's nose. The dental hood fits close to the face to reduce gas escaping into the dental office. Most of these hoods are subjected to time consuming cleaning and are reused. As discussed above, chemicals such as glutaraldehyde are usually used to disinfect the mask and to remove cosmetics, drugs, viruses, bacteria, mold and other unwanted materials, so these agents are not transferred to the next patient. In this regard, it is important to note that aldehydes have been implicated as having carcinogenic activity.
In the last few years small vacuum or scavenging systems have been added to dental hoods to aid in the removal of nitrous oxide that escapes from old style hoods. The addition of these systems has made cleaning harder, more time consuming, and in some cases, almost impossible. In many cases more cleaning time means more contact time of cleaning chemicals that may accelerate the deterioration of the gas hood. With this problem and the development of knowledge of the existence of the AIDS virus and other agents that could be transferred from patient to patient, a need was recognized for a disposable material to fill the gap between the gas delivery appartus and the patient. This disposable material should allow free gas exchange but reduce direct contact between the apparatus and the patient.